Are you interested in reasonable transport via Alaska Marine Hiway (aka,
the ferry!)? If you don't book cabin passage, it is cheap &I believe reservations
are now being accepted.
There's a book called Alaska Milepost which will give you tons of good
info &contacts for day tours in SE Alaska.
Stock up on polar fleece & rain gear, but be prepared for nice weather
as well; last year, early May had no rain &temps in the 60's!
Sitka is wonderous anytime, with some nice walking paths (not rigorous,
but easy) thru some lovely rainforest.